Neurological investigations

Question 1

common investigations

Answer 1

routine blood tests
special blood tests (including autoantibodies)
molecular genetic tests
imaging - CT, MRI, angiography/venography, doppler ultrasound, nuclear medicine
CSF examination
neurophysiology
biopsy

Question 2

what is the first line imaging

Answer 2

CT
it can detect cerebral tumours, intracerebral haemorrhage, mature infarcts, subdural and extradural haematoma, free blood in subarachnoid space, lateral shift of midline structures, displacement or enlargement of ventricles, cerebral atrophy, intracranial calcification, skull and scalp lesions

Question 3

problems with CT

Answer 3

radiation
may miss lesions under 1cm
lesions with attenuation similar to brain are poorly imaged
poor grey-white matter differentiation
lesions with attenuation close to bone may be missed
can miss lesions within the posterior fossa
spinal cord is not imaged directly

Question 4

what are the advantages of MRI

Answer 4

distinguishes between grey and white matter
spatial resolutions allow imaging of spinal cord, nerve roots and large nerves
greater resolution than CT
no radiation
can see blood vessels without contrast
can scan posterior fossa, pituitary gland and foramen magnum
can see focal atrophy

Question 5

limitations of MRI

Answer 5

time
cost
patients need to cooperate
claustrophobia
general anaesthetic may be needed
cant have metal
possible overinterpretation of changes

Question 6

what is CSF examination used for

Answer 6

diagnosis of neurological infection
study of blood products following suspected SAH
aid to diagnosis of inflammatory and neurodegenerative disorders
measurement of CSF pressure

Question 7

what does typical CSF look like

Answer 7

crystal clear
less than 5wbc per mm^3
protein is 0.2-0.4g/l
glucose is usually 2/3-1/2 of blood glucose
culture is sterile
oligoclonal bands are absent
IgG is less than 15% of total CSF protein

Question 8

complications of lumbar puncture

Answer 8

low-pressure headaches
intracranial subdural haematoma
local infection and meningitis
trauma - local pain, nerve root damage
bleeding
spinal epidural haematoma
arachnoiditis

Question 9

what is electromyography used for

Answer 9

diagnosis of radiculopathies, anterior horn cell disease, neuropathies, NMJ pathology, myopathies

Question 10

how is electromyography performed

Answer 10

needle electrode is inserted into voluntary muscle
amplified recording from muscle is viewed on a oscilloscope and heard through a speaker

Question 11

what are the 3 main features seen and recorded on an electromyography

Answer 11

normal motor recruitment
denervation and reinnervation changes
myopathic, myotonic, myasthenic and other changes

Question 12

what do nerve conduction studies measure

Answer 12

motor conduction velocity
sensory conduction velocity
distal motor latency
sensory (nerve) action potentials
compound muscle action potentialsh

Question 13

what are the types of neuropathy

Answer 13

demyelination
conduction block
axonopathy (damage to nerve axon)
vasculitic